Bitcoinproof creates a forgery-proof timestamp for your data, secured by the Bitcoin network. It allows you to prove that a certain event happened before a certain point in time. Maybe you want to prove that the damage in your flat already existed when you moved in, or that you were in possession of a great artwork before it was published, proving you are the author.
CryptSharp provides a number of password crypt algorithms: BCrypt, MD5 (and Apache's htpasswd variant), PHPass (WordPress, phpBB, Drupal), SHA256, SHA512, and Traditional and Extended DES. It also includes Blowfish, SCrypt, and PBKDF2 for any HMAC (.NET's built-in PBKDF2 implementation supports only SHA-1). If you are looking to store passwords, odds are CryptSharp will have the algorithm you want.
Lhasa is a Free Software replacement for the Unix LHA tool, for decompressing .lzh (LHA/LHarc) and .lzs (LArc) archives. The backend for the tool is a library, so it can be reused for other purposes. Lhasa aims to be compatible with as many types of lzh/lzs archives as possible. It also aims to generate the same output as the (non-free) Unix LHA tool, so it will act as a drop-in free replacement.